Interlayer exchange coupling

The extensive research done on interlayer exchange coupling in transition m etal multilayers has resulted in a deep understanding of this coupling and a remarkable agreement between theoretical results and measurements. The co upling between two magnetic layers separated by a non-magnetic spacer layer is mediated by the electrons of the spacer layer. The coupling, which osci llates in sign as a function of the thickness of the spacer layer, is close ly related to the well-known RKKY interaction between magnetic impurities. Due to the existence of many high-quality measurements, it has been much mo re fully developed theoretically than the interaction between impurities. T heory predicts that the periods of the oscillatory coupling should depend o n critical spanning vectors of the Fermi surface belonging to the spacer-la yer material There is remarkable agreement far the measured periods and tho se predicted from the Fermi surfaces. There is also substantial agreement b etween theory and experiment on the strength of the coupling. This review p resents the comparison between theory and experiment in some detail. (C) 19 99 Published by Elsevier Science B.V. All rights reserved.